The rough South African seas could provide enough electricity for a city, a new study finds

Business Insider SA

Ocean. (Duncan Alfreds, News24, file)
Photo: Duncan Alfreds
  • Ocean turbines in the Agulhas Current, which hugs South Africa’s east coast, could help the country produce baseload energy when it decommissions its coal-fired plants 
  • The optimal place for the turbines would be about 100km north-east of East London, but more studies are needed to see how expensive it would be
  • Other countries are looking to install renewable ocean energy, with plans to install 1MW capacity off the shore of Florida in the US.
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Giant turbines in the ocean off East London’s coast could be a “green” solution to providing baseload electricity. The Agulhas Current, a strong flow of water that follows South Africa’s eastern flank, is a renewable energy source which could be tapped using turbines moored in the ocean.

At the moment, South Africa relies on coal-fired power stations for its baseload energy, but this is going to change. According to the government’s energy plans, South Africa will soon be decommissioning its coal plants, with coal-derived energy expected to contribute less than 30% of total energy supply by 2040 and less than 20% by 2050.

“Given South Africa’s resource rich environment, there are a number of renewable energy technologies that are commercially viable at present, however the need for a baseline renewable energy resource persists,” says Imke Meyer, an energy engineer.

A study, published by Meyer and a colleague in the International Journal of Marine Energy, has found that the best spot for turbines would be about 100km north-east of East London. The three key technical points to consider are how fast the current flows, its distance from shore at this point, and it depth, she says.

“The Agulhas Current is so big and powerful that such turbines would not really impact on [the current’s strength and the ocean environment],” says Marjolaine Krug, a senior researcher at the Council for Scientific and Industrial Research. She does note, though, that this would depend on the number of turbines deployed.

Source: South African Environmental Observation Network (SAEON)

“I think part of the initial implementation plan, if this was deemed a good idea to pursue, would be to perform tests with turbines and conduct environmental impact assessments,” she says.

Both Meyer and Krug warn that such an installation could be expensive, though, as the technology is fairly immature. “Although a number of lessons learnt can be transferred from tidal energy technology development and off-shore wind turbine installations, the unique challenges - such as installing turbines in a non-stop swift current and significantly deeper mooring depth than tidal applications as well as the technology maturity level - will need to be assessed to quantify the cost of generating electricity with this resource,” says Meyer.

However, earlier this year, US company OceanBased Perpetual Energy signed a memorandum of understanding with Florida Atlantic University’s Southeast National Marine Renewable Energy Center, with a view to building “the world’s largest commercial ocean current energy project”.

Following a testing phase, the project expects to install up to 1MW capacity and connect it to shore, and expand to up to 20MW within about five years, according to HydroReview.

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